Slack, the $7 billion office-messaging app that millennials and startups love, just filed to go public in a really weird way

Slack, the buzzy workplace-chat platform last valued at over $7 billion, filed the paperwork on Friday to publicly list its shares.

The company has tapped into an interesting new trend for tech firms going public, saying it would do a "direct listing" that avoids the usual Wall Street IPO process. The startup plans to directly list its shares on the New York Stock Exchange under the ticker symbol SK.

Slack reported a net loss of $146 million on $105.2 million in revenue for its fiscal 2017, then a net loss of $140 million on $220.5 million in revenue for 2018, and a $138.9 million loss on $400.6 million in revenue for fiscal 2019.

The company, which makes its money mostly from monthly or annual subscriptions, said it has 88,000 paying customers, 575 of which bring in more than $100,000 in recurring yearly revenue and make up 40% of its business.

It's one of the most hotly anticipated offerings in a year of blockbuster tech IPOs including Uber, Lyft, Pinterest, and Zoom.

Slack, the workplace-chat platform that's taken offices by storm, filed the paperwork on Friday to go public, kicking off the final countdown to its listing and shedding light on the financial happenings at one of Silicon Valley's most valuable startups.

Slack was last valued at about $17 billion on secondary-market trades, CNBC reported. It was officially valued at $7.1 billion after its latest financing round, last August.

In its S-1 filing, Slack said it planned to list on the New York Stock Exchange under the ticker symbol SK through a direct listing, a unique alternative to the initial public offering in which private shareholders such as investors and employees sell their holdings directly to the public.

The company said $100 million worth of shares would be sold, though that's most likely a placeholder number.

Unlike in a standard IPO, Slack won't raise a bunch of new cash from investors rushing to buy its stock, and it won't set a share price.

Slack is trimming its losses but says it may never be profitable

The firm also lifted the lid on its financial performance over the past three years.

During the year ended January 31, 2017, Slack lost $146 million on $105.2 million in revenue.

The following year it lost $140 million on $220.5 million in revenue.

And in the year ending January 31, 2019, it lost $138.9 million on $400.6 million in revenue.

The company, which makes money predominantly from monthly or yearly subscriptions, said it counts 88,000 paying customers, 575 of which account for more than $100,000 in recurring yearly revenue and make up 40% of Slack's total business. The startup said it has more than 500,000 organizations on its free tier.

The firm wrote: "We expect to continue to incur net losses for the foreseeable future and we may not achieve or maintain profitability in the future.

"Because the market for Slack, and the features, integrations, and capabilities we offer on Slack, is rapidly evolving and has not yet reached widespread adoption, it is difficult for us to predict our future results of operations or the limits of our market opportunity."

The company said it expected a significant increase in operating expenses thanks to hiring and development.

Slack said it has more than 10 million daily active users globally, with more than half outside the US.

Slack has always billed itself as an email killer and, listing the risks to its business, said that email was a competitor.

The firm also listed Microsoft as its primary competitor and described Google, Facebook, and Cisco as business-software rivals. It also said existing partners such as Atlassian, Okta, Oracle, ServiceNow, SAP, Workday, Zoom, and Salesforce were potential direct or indirect rivals.

It's a banner year for tech IPOs

Slack will be the latest in the parade of unicorn tech companies — named as such for their $1 billion-plus valuations — to go public this year.

The ride-hailing company Lyft went public at the end of March in an IPO that valued the company at $21 billion. It was followed by the IT-management company PagerDuty, which was valued at $1.76 billion.

Last week brought two IPOs: the videoconferencing company Zoom, with a $9 billion valuation, and the online-scrapbooking platform Pinterest, which was valued at $10 billion.